Drawout apparatus are well-known expedients for facilitating the installation and removal of physically large electrical devices, such as switches and circuit breakers, with respect to switchboards and the like. The devices are equipped with plug-in or stab-type disconnect primary contacts which mate in electrical interconnection with complementary switchboard primary disconnect contacts incident to racking movement of the device to its innermost, engaged position, thereby making the electrical joints requisite to electrically connecting the device into the switchboard.
The principal limitation to the utilization of drawout apparatus is the ability of the plug-in primary terminal joints to carry the increasingly higher currents called for in many applications. These joints invariably constitute sources of heat which can contribute to an intolerable high temperature condition within the switchboard. The spring forces incorporated in such plug-in terminal connectors and their mutual contact surface areas, which will accommodate sliding relative movements of the mating connectors incident to making and breaking the joints, are not sufficient to achieve cool-running joints in high current applications. The most practical approach to achieving cool-running joints is to resort to bolted interconnections. However, such bolted joints for drawout installations sacrifice the advantage of being able to connect and disconnect the device from a live switchboard without having to operate directly on the primary terminal joints.
It is accordingly an object of the present invention to provide improved electrical joint apparatus of high current capacity having particular but not limited application in switchboard drawout apparatus.
An additional object of the present invention is to provide electrical joint apparatus of the above character which is operable to simultaneously make a plurality of electrically isolated high current carrying electrical joints.
A further object of the present invention is to provide electrical joint apparatus of the above character, which is operable to make plural, reliable electrical joints in highly repeatable fashion.
Yet another object of the present invention is to provide joint apparatus of the above character, which is capable of perfecting electrical joints having all of the characteristics and attributes of bolted joints.
An additional object is to provide electrical joint apparatus of the above character which is efficient in design and conveniently manually operable in a rapid fashion.
Other objects of the invention will in part be obvious and in part appear hereinafter.